Research On Urban Storm Drainage System Optimization Design Based On Sponge City Concept

With the development of urbanization,the traditional urban storm drainage system which takes the drainage load has increased,the urban waterlogging disasters occur frequently.In order to ensure the safety of urban drainage and protect the ecological environment,the Ministry of Housing and Urban-Rural Development began to promote the sponge city construction.The standards for planning,design,construction and management of urban storm drainage system have improved.Therefore,this paper studies the optimal design method of urban storm drainage system based on sponge city concept.Firstly,the research progress of sponge city and urban storm drainage system optimization design is discussed in this paper.Based on the theory of urban rainwater system,the design criteria such as design recurrence interval,runoff coefficient and annual total runoff volume control rate have been analyzed,which provided a guidance for the follow-up study.Secondly,the sponge city measures with functional characteristics,applicable conditions and scale calculation method are introduced.According to the standards of sponge city construction guide and code for design of outdoor wastewater engineering,the optimization target is determined from the whole,with the restrictions from annual total runoff volume control rate,the design parameters of storm drainage pipe and the design index of local flooding control.A reasonable scale optimization model which comprises with source emission reduction,storm drainage and stormwater storage pool is created,thus achieving a reasonable optimization result for the entire construction of sponge city.And the influence which is sponge city construction on the urban storm drainage system optimal design,was analyzed from the aspects of the composition of urban storm system,the total runoff volume and the peak runoff volume.Finally,the multi-objective optimization model of urban stormwater pipe network based on sponge city concept is established.The objective functions include the total cost of stormwater pipe network,total overflow and floading time.The multi-objective is transformed into single target by weighting method,using genetic algorithm and SWMM Source code,and based on Matlab for optimal solution.In the end,a case of some study area in Hefei is given,then the SWMM model of stormwater pipe network is established,and the optimal design scheme is obtained by genetic algorithm.